A laser radar (also called LIDAR, LiDAR and LADAR) is a device that measures distance to a target by illuminating that target with a laser (e.g., ultraviolet, visible, or near infrared). A laser radar may be used to image objects, which may include a wide range of materials, including non-metallic objects, rocks, rain, chemical compounds, aerosols, clouds and even single molecules.
A laser radar may include a laser (e.g., a laser with a wavelength between 500 nm and 1600 nm). The laser may be pulsed or continuous. A laser radar may include a mechanism that scans and controls the laser. The mechanism may scan the laser mechanically (e.g., oscillating plane mirrors, polygon mirrors) or electronically (e.g., phased array). A laser radar may also have a detector configured to detect light reflected by the objects being imaged.
The vertical-cavity surface-emitting laser (VCSEL), is a type of semiconductor laser diode with laser beam emission perpendicular from the top surface, contrary to conventional edge-emitting semiconductor lasers (also in-plane lasers) which emit from surfaces formed by cleaving the individual chip out of a wafer. A VCSEL may have an active region sandwiched between upper and lower Bragg reflectors (e.g., formed by epitaxial growth on a substrate). A VCSEL may be formed from materials such as GaAs, InGaAs, or AlGaAs.